daytona bike week 07

  • Thread starter Thread starter ARCHIVE_Harriminator
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ARCHIVE_Harriminator

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main jets in carbs of the ZL9

Hi folks,
a question in the German forum about the ZL9-carbs let me look into the partlist and I was surprised to find beside the orig. main jet 125 four more pieces marked with A to D and sizes of 120, 122, 128 and 130. There is no spec. code added like US or CA or CN so from my Dyno-jet kit I know Stage 1 has the 108+112 and the Stage 3 has 132+136, always in combination with the kit-needles and possible changing of airfilters+exhaust.
Seems Kawa has something similar for playing with needles position etc....? Who knows more? Really strange... :roll:

Greets, Harriminator.
 
From what I now understand, and have surmised, regarding the ZL900…

…Kawasaki engineers had already perfected, and knew, that the CVK-32 carburetors performed exceptionally well with a wide-open throttle in the low to midrange rpm area, especially with the taper of the N27N needles. So, because the bike was designed and proven in a time, and in a country without “noise level” or “environmental” restrictions in place, performance engineering became their paramount focus, but simply had to take a back seat in order to pass foreign set standards; hence, the bike was then de-tuned to pass emissions and noise level restrictions, enabling it to enter the USA, and other foreign markets. The easiest way to achieve these foreign set standards for exportation was to drop the main jet size down, and add some emissions equipment.

Once purchased, adjusting the throttle response for the quarter mile simply required an adjustment of the ¾ to full throttle area, going from the stock #125 main-jet back to a #130 main-jet cures this problem, without changing needles. Kawasaki made the parts available to the end user, enabling him/her to retune the bike.

In my case, for a ZL900 using aftermarket Holeshot mufflers, K&N air filters, and a 4-degree timing advancer…this is what really works!

…Stock main-jet was #125, turned out 2-1/8 turns from the factory, I now run #135 main-jets, turned out 3 full turns, bear in mind, this fuel is pouring into the smaller stock CVK-32 Carburetors, extremely low end torque-r’s, as for the CVK-34 carburetors, that are used on the ZX900, and ZL1000, I really couldn’t tell you what aftermarket sizes they are running. Dyno says a stock rear wheel in high gear @ redline is 122 mph, the best I can hope for here is about a 10.98 ET in the quarter mile, without a wheelie bar, on an exceptional run.

Using the stock needles, N27N, I simply added three brass shims over the tip of each needle, and hang on, pulls like a freight train from 2500 rpm up to the red line, no flat spots, as may be experienced using different needle sizes.

"Carb tuning"

"Actual Dyno"

I hope this information may help some,

Brian
 
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